Method of forming enlarged base encased concrete piles

ABSTRACT

A METHOD OF FORMING ENLARGED BASE PILES BY FORMING A CYLINDRICAL HOLE IN THE GROUND, AND THEREAFTER PLACING A CHARGE OF BULK MATERIAL SUCH AS ZERO SLUMP CONCRETE IN THE BOTTOM OF THE HOLE, AND THEN PLACE A PILE SHELL WITH A CLOSED TIP OVER THE MANDREL AND DRIVING IT INTO THE HOLE AND INTO THE CHARGE OF MATERIAL, AND THEREAFTER WITHDRAWING THE MANDREL AND FILLING THE SHELL WITH CONCRETE.

METHOD OF IE'ORMIIK'I ENLARGED BASEJENCASED CONCRETE FILES Filed July 15, 1968 F..M. FULLER Feb. 2, 1971 4 Sheets-Sheet 1 HIIIIIIIIII IIIHHH H HP METHOD OF FORMING ENLARGED BASE ENCASED CONCRETE PILES Filed July 15, 1968 4 Sheets-Sheet 2 r/ I I I [1y mH HLI AL HP A A770 A 06 F. M. FULLER METHOD OF ,FORMING ENLARGED BASE ENCASED CONCRETE PILES 4 sheets-sheet 5 Filed July 15, 1968 Rm 2 N0 w M M m F "METHOD OEFORMING ENLARGED BASE ENCASED CONCRETE PILES Filed July 15, 1968 FbfZ, 1971 F. M. FULLER 4 Sheets-Sheet 4 United States Patent 3,559,412 METHOD OF FORMING ENLARGED BASE EN CASED CONCRETE PILES Frank M. Fuller, Washington Township, Bergen County, N.J., assignor to Raymond International, Inc., New

York, N.Y., a corporation of New Jersey Filed July 15, 1968, Ser. N 0. 744,846 Int. Cl. E02d 5/44 US. Cl. 6153.6 12 Claims ABSTRACT OF THE DISCLOSURE A method of forming enlarged base piles by forming a cylindrical hole in the ground, and thereafter placing a charge of bulk material such as zero slump concrete in the bottom of the hole, and then placing a pile shell with a closed tip over the mandrel and driving it into the hole and into the charge of material, and thereafter withdrawing the mandrel and filling the shell with concrete.

This invention has to do with a new and improved method of forming encased concrete piles, and more particularly to a method of forming cast-in-place concrete piles having an enlarged base.

It has been found that the load bearing capability of concrete piles can often be increased by enlarging their lower ends. Several methods have been employed for forming such enlarged lower ends, such as, for example, positioning the casing in the ground, pouring a charge of wet concrete in the bottom of the hole, and then exerting pressure on the concrete to expand it. Also, it is known to ram out successive charges of concrete from a drive casing.

An object of this invention is to provide such a method which is an improvement over the methods heretofore known. Briefly, my invention contemplates a method of forming a concrete pile by first driving a mandrel down into the earth into the bearing stratum. In one form of the invention, a steel mandrel of the required size and configuration is driven with a conventional pile driving hammer. Actually, this step is well-known in the art and is often referred to as spudding. The mandrel is predriven at the site of the pile, thereby providing a number of benefits such as pushing aside any obstructions that might be present in the soil, reducing the drag of the soil on the pile as it is driven, and reducing the back pressure experienced by the driven pile, for example. The present application is directed to the spudding operation in soils which produce a hole which stays open after the spud is withdrawn. However, in some applications the soil may be unstable and a partial or a full sleeve is employed. In other soils it may prove advantageous to predrill rather than pre-spud the hole.

The next steps in my method involve withdrawing the mandrel and, if a temporary sleeve is utilized, dropping it into the hole. Thereafter, a charge or plug of bulk material is placed in the bottom of the hole formed by the mandrel. In one form of the invention the charge comprises zero slump concrete which may be of the order of about 5 cubic feet or more in size. The advantage of utilizing a concrete plug is that it adds structurally to the pile because it sets-up and hardens. Only suflicient water is necessary to hydrate the cement. Other materials may be used in place of the concrete, such as crushed stone or rubble-like material, for example.

Thereafter, a pile shell with a closed tip is placed over a mandrel and driven into the hole and into the charge of concrete at the bottom of the hole to force it downwardly and outwardly into the shape of an enlarged base. In one form of my invention a corrugated steel pile ice shell, such as is supplied by Raymond International, Inc., under their trademark Step-Taper, is used and the mandrel is shaped so as to engage the shell at the steps for driving purposes. In addition to the normal compaction of the soil by the driving of displacement type piles, additional densification and improvement of the soils within the bearing stratum is obtained by the displacement of the concrete plug. When the enlarged base is formed by the use of rubble or the like, the bearing stratum in the ground is improved by the intrusion of this material under the driving, and is thereby better able to develop a point support for the pile. When a cementitious mixture is used for the enlarged base, a bond is developed between the tip of the pile and the cementitious mass so that when the enlarged base cures'with time, the pile distributes the load from the pile shaft over a larger area within the bearing stratum, and consequently increases its load bearing capability. Hence, it will be appreciated that the forming of the base and the making of the connection between the base and the pile are completed in one operation, and that there is a positive connection between the pile and the base.

In particular installations where pile heave conditions are encountered, tell-tale readings can be taken on the pile tip and, when necessary, the pile may be retapped to compensate for heave. In addition, as pointed out hereinbefore, when the pile has to be installed through unstable soils, a temporary sleeve or casing may be used which may be withdrawn later. Also it is possible to use a short piece of pipe at the bottom of the shell to provide greater strength against collapsing pressures created when the pile tip is driven into the concrete plug. It will be appreciated that in some predrilling instances, the hole will be full of water. In this event, the zero slump concrete may be added in a preformed plastic sack which could be lowered through the water to the bottom of the hole. The ultimate driving of the finished pile would burst the sack and disburse the material. If rubble base material is used, then it is not necessary to put the rubble material in a plastic sack when forming the base through water.

The next step, after final driving, according to my invention, is withdrawing the temporary sleeve if one is employed, and then withdrawing the mandrel leaving the shell in the ground with the tip embedded in the concrete base. At this time the shell may be inspected internally. In view of the fact that the pile is driven with a closed end, it may be made water-tight to exclude ground water, thereby permitting full internal inspection and the proper placement of the concrete filling. Concrete reinforcing means may be inserted in the shell at this time, if desired. Thereafter, the shell is filled with concrete, and as a last step, the excess shell, if any, may be removed. That is, if an excess portion of the shell protrudes about the ground, it may be trimmed to the desired level.

It will be appreciated that it is not essential to use a mandrel and shell of downwardly decreasing stepped configuration. A straight sided mandrel could be used to drag down either a corrugated shell or a plain thin wall pipe. This is especially true Where a temporary sleeve is used to hold back the unstable soil. Even a straight sided expandable mandrel could be used.

There has thus been outlined rather broadly the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter which will form the subject of the claims -ap pended hereto. Those skilled in the art will appreciate that the conception on which this disclosure is based may readily be utilized as the basis for the design of other 3 structures for carrying out the several purposes of the invention. It is important, therefore, that the claims he regarded as including such equivalent constructions as do not depart from the spirit and scope of the invention.

Several embodiments of the invention have been chosen for purposes of illustration and description, and are shown in the accompanying drawings, forming a part of the specification, wherein:

FIG. 1 is a vertical sectional view of a mandrel disposed in a hole driven in the earth;

FIG. 2 is a view similar to FIG. 1, but showing the mandrel withdrawn and a charge of zero slump concrete inserted in the hole;

FIG. 3 is a view similar to FIG. 2, but showing the mandrel with a pile shell inserted thereover disposed in the hole driven in the earth;

FIG. 4 is a view similar to FIG. 3, but showing the mandrel withdrawn;

FIG. 5 is a view similar to FIG. 4, but showing the pile shell with concrete disposed therein;

FIG. 6 is a vertical sectional view of a mandrel disposed in a hole driven in the earth according to another embodiment of my invention;

FIG. 7 is a view similar to FIG. 6, but showing a temporary sleeve inserted in the hole in the earth;

FIG. 8 is a view similar to FIG. 7, but showing a charge of concrete inserted in the hole;

FIG. 9 is a view similar to FIG. 8, but showing a mandrel with a pile shell inserted thereover disposed inside of the sleeve within the hole in the earth;

FIG. 10 is a view similar to FIG. 9, but showing the temporary sleeve withdrawn;

FIG. 11 is a view similar to FIG. 10, but showing the mandrel withdrawn;

FIG. 12 is a view similar to FIG. 11 but showing the pile shell with concrete disposed therein;

FIG. 13 is a vertical sectional view through a mandrel with a pile shell and a portion of a short pipe thereover disposed in a hole driven in the earth according to another embodiment of my invention;

FIG. 14 is a view similar to FIG. 13 but showing the mandrel withdrawn;

FIG. 15 is a view similar to FIG. 14 but showing the pile shell with concrete disposed therein;

FIG. 16 is a vertical sectional view of a mandrel and temporary sleeve disposed in a hole driven in the earth according to another embodiment of my invention;

FIG. 17 is a view similar to 16, but showing the mandrel removed and a charge of concrete inserted in the hole;

FIG. 18 is a view similar to FIGS. 16 and 17, but showing a mandrel with a pile shell inserted thereover disposed inside of the sleeve in the hole in the earth;

FIG. 19 is a view similar to FIG. 18, but showing the temporary sleeve and the mandrel withdrawn; and

FIG. 20 is a view similar to 19, but showing the pile shell with concrete disposed therein.

In the embodiment of the invention illustrated in FIGS. 1-5, a mandrel 10 having a downwardly decreasing stepped configuration is driven down into the earth 12 into the bearing stratum, as best seen in FIG. 1. Then, as seen in FIG. 2, the mandrel 10 is withdrawn and a charge of zero slump concrete 14 is placed in the bottom of the hole 16 formed by the removal of the mandrel. Referring next to FIG. 3, a pile shell 18, which is preferably corrugated, is placed over the mandrel 10. The shell is provided with a mating configuration with respect to the mandrel so that the mandrel engages the shell at the steps, as at 20 and 22, so that the shell can be driven into the hole 16 previously formed. It will be appreciated that since the shell is placed over the mandrel, the hole 16 will be slightly enlarged, thereby densifying and improving the soils disposed adjacent the pile when it is in its final position. The pile shell 18 is provided with a closed tip 24 which is driven into the charge of zero Cir 4, slump concrete 14 at the bottom of the hole when the mandrel and shell are driven into the hole, thereby forcing the concrete downwardly and outwardly forming an enlarged base.

The next step is shown-in FIG. 4. and comprises the removal of the mandrel, the shell 18 being left in the hole and the tip 24 remaining'emb edded in the concrete base. Since the shell is closed, it may be internally inspected. Internalreinforcement members 25 may be positioned in the shell 18 for adding strength to the concrete. Thereafter, as best seen in FIG. 5, the shell'18 is filled with concrete 26 and the top 28 of the shell may be trimmed if there is an excess. The enlarged base pile is now ready for use.

The method according to the embodiments of my invention illustrated in FIGS. 6-12is particularly desirable for use with unstable soil conditions. As best seen in FIG. 6, a mandrel 30 of generally cylindrical con figuration is pre-driven down into the earth 32 into the bearing stratum at the pile site. Thence, the mandrel is withdrawn and a temporary sleeve 34 is lowered into the hole 36 formed by the removal of the mandrel, as seen in FIG. 7. In one form of my invention the mandrel and the temporary sleeve are driven together down into the earth into the bearing stratum, and then the mandrel is withdrawn. In another form the mandrel, the temporary sleeve and a pile shell are all simultaneously driven down into the earth 32 into the bearing stratum at the pile site, and thence the mandrel and the pile shell are withdrawn. These alternate forms serve to eliminate one or more steps in the method. As a next step, a charge of zero slump concrete 38 is placed in the bottom of the hole 36, FIG. 8. Then a corrugated pile shell 40 having a downwardly decreasing stepped configuration is placed over a mandrel 42 having a mating stepped configuration and is driven into the hole 36 inside the sleeve 34, FIG. 9. It will be appreciated that the mandrel and the .pile shell may be the same elements as previously withdrawn. The pile shell is provided with a closed tip 44 which engages the concrete 38 and forces it outwardly and downwardly forming an enlarged base. As best seen in FIG. 10, the temporary sleeve 34 is withdrawn from the hole '36 leaving the mandrel 42 and pile shell 40 therein. Then, as

seen in FIG. 11, the mandrel 42 is withdrawn leaving the pile shell 40 in the hole. It will be appreciated that this method is normally used with unstable soil conditions, and hence the soil 32 will move inwardly and firmly en, gage and hold the shell such as from its position shown in FIG. 10 to its position shown in FIG. 11. Thereafter, concrete 46 is placed in the shell and the top of the shell may be trimmed as at 48, FIG. 12, if desired.

FIGS. 13, 14 and 15 illustrate another embodiment of my invention which provides greater strength against collapsing pressures created when the pile tip is driven into the cement plug. First a hole 16 is prepared in the same manner as described hereinbefore in connection with the description of FIGS. 1 and 2. However, in this embodiment a short straight piece of pipe 48 is positioned at the bottom of a shortened corrugated pile shell 50, the pipe 48 having a closed tip 52. The pipe 48-and the pile shell 50 are placed over the mandrel 10 and driven into the hole 16 and into the charge of zero slump concrete 14, FIG. 13. Thence, the mandrel 10 is withdrawn leaving the pipe 48 and the pile shell 50 in the hole, FIG. 14. Thelast stepis to fill the pipe and the pile shell with concrete 54, FIG. 15, thereby completing the pile.

In the embodiment of FIGS. 1620, a radially expandable mandrel 56, such as one described in U.S. Pat. No.

2,684,577 or US. Pat. No. 2,741,093, is inserted inside a temporary sleeve 58 and expanded to engage the temporary sleeve. Then, as best seen in FIG. 16, themandrel and sleeve are driven together down into the earth 60 into the bearing stratum at the pile site. Thence, the'mandrel is withdrawn and a charge of zero slump concrete 62 is placed in the bottom of the hole 64, FIG. 17. Then, the

mandrel 56 is retracted to fit inside a cylindrical corrugated pile shell 66, and the mandrel and shell are driven together into the hole 64 inside the sleeve 58, FIG. 18. The pile shell is provided with a closed tip 68 which engages the concrete 62 and forces it outwardly and down wardly forming an enlarged base. The temporary sleeve 58 is withdrawn and then the mandrel 56 is withdrawn from the hole 64 leaving the pile shell 66 in the hole. Since the shell is closed, it may be internally inspected and reinforcement members (not shown) may be added. Thereafter, as best seen in FIG. 20, the shell 66 is filled with concrete 70 and the top 72 of the shell may be trimmed if there is an excess. The enlarged base pile is now completed.

It will thus be seen that the present invention does indeed provide a new and improved method of forming enlarged base piles which is superior in simplicity, economy and efiiciency as compared to prior art methods.

Although certain particular embodiments of the invention are herein disclosed for purposes of explanation, various modifications thereof, after study of this specification will be apparent to those skilled in the art to which the invention pertains, and reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A method of forming an enlarged base pile comprising the steps of driving a mandrel down into the earth, withdrawing the mandrel, placing a charge of bulk material in the bottom of the hole, placing a pile shell with a closed tip over a mandrel and driving it into the hole and into said charge to enlarge the base, withdrawing the mandrel, and filling the shell with concrete.

2. A method of forming an enlarged base pile according to claim 1 wherein said bulk material is zero slump cement.

3. A method of forming an enlarged base pile according to claim 1 wherein said bulk material is crushed stone.

4. A method of forming an enlarged base pile according to claim 1 further comprising the step of positioning internal reinforcement members inside said pile shell subsequent to withdrawing the mandrel and prior to filling the shell with concrete.

5. A method of forming an enlarged base pile according to claim 1 further comprising the step of removing excess shell at the top thereof.

6. A method of forming an enlarged base pile com prising the steps of driving a mandrel having a downwardly decreasing stepped configuration down into the earth into the bearing stratum, withdrawing the mandrel, placing a charge of bulk material in the bottom of the hole, placing a mating stepped pile shell with a closed tip over said mandrel and driving it into the hole and into said charge to enlarge the base, withdrawing the mandrel, and filling the shell with concrete.

7. A method of forming an enlarged base pile comprising the steps of driving a mandrel down into the earth into the bearing stratum, withdrawing the mandrel, placing a temporary sleeve in said hole, placing a charge of bulk material in the bottom of the hole, placing a pile shell with a closed tip over a mandrel and driving it inside said sleeve into the hole and into said charge to enlarge the base, withdrawing said temporary sleeve, withdrawing the mandrel, and filling the shell with concrete.

8. A method of forming an enlarged base pile comprising the steps of driving together a mandrel and a temporary sleeve down into the earth into the bearing stratum, withdrawing the mandrel, placing a charge of bulk material in the bottom of the hole, placing a pile shell with a closed tip over a mandrel and driving it inside said sleeve into the hole and into said charge to enlarge the base, withdrawing said temporary sleeve, withdrawing the mandrel, and filling the shell with concrete.

9. A method of forming an enlarged base pile comprising the steps of driving together a mandrel, a temporary sleeve and a pile shell down into the earth into the bearing stratum, Withdrawing the mandrel and the pile shell, placing a charge of bulk material in the bottom of the hole, inserting together said mandrel and said pile shell into the hole and into said charge to enlarge the base, withdrawing said temporary sleeve, withdrawing the mandrel, and filling the shell with concrete.

10. A method of forming an enlarged base pile comprising the steps of inserting a mandrel inside a temporary sleeve to engage said temporary sleeve, driving together said mandrel and said temporary sleeve down into the earth into the bearing stratum, Withdrawing the mandrel, placing a charge of bulk material in the bottom of the hole, retracting said mandrel to fit inside a pile shell, driving said mandrel and pile shell inside said sleeve into the hole and into said charge to enlarge the base, withdrawing said temporary sleeve, withdrawing the mandrel, and filling the shell with concrete.

11. A method of forming an enlarged base pile comprising the steps of driving an enlarged cylindrical shaped mandrel down into the earth into the bearing stratum, withdrawing the mandrel, placing an elongated cylindrically shaped sleeve in said hole, placing a charge of bulk material in the bottom of the hole, placing a pile shell having a downwardly decreasing stepped configuration and a closed tip over a mating stepped mandrel and driving it inside said sleeve into the hole and into said charge to enlarge the base, withdrawing said sleeve, withdrawing the mandrel, and filling the shell with concrete.

12. A method of forming an enlarged base pile comprising the steps of driving a mandrel having a downwardly decreasing stepped configuration down into the earth into the bearing stratum, withdrawing the mandrel, placing a charge of bulk material in the bottom of the hole, placing a short straight pipe with a closed bottom end over the lower end of said mandrel, and placing a mating stepped pile shell over the remainder of said mandrel, and driving the mandrel, pipe and shell into the hole and into said charge to enlarge the base, withdrawing the mandrel and filling the pipe and shell with concrete.

References Cited UNITED STATES PATENTS 1,775,217 9/1930 Thornley 6153.6 2,027,511 1/1936 Bertran 6l--53.6 X 3,187,513 6/1965 Guild 6l53.7 X 3,074,240 1/ 1963 Elliott 6l53.6 X

JACOB SHAPIRO, Primary Examiner U.S. Cl. X.R. 6153.66 

